[2] Amanieu was made a cardinal deacon in the consistory of 20 March 1500 by Pope Alexander VI.
[2] After Cardinal Giuliano della Rovere sought refuge in Savona, Amanieu was secretly despatched on 21 June 1502 to bring him back, but failed in this mission.
[2] Amanieu participated in both the papal conclave of September 1503 that elected Pope Pius III, and the papal conclave of October 1503 that elected Pope Julius II.
[2] Amanieu participated in the plot of cardinals against Pope Julius II.
[2] After the death of Julius II, he did not participate in the papal conclave of 1513 that elected Pope Leo X.